Method and apparatus for filling aerosol dispensers



H. 2. SOKOL Feb. 1, 1966 METHOD AND APPARATUS FOR FILLING AEROSOLDISPENSERS Filed Jan. 18, 1965 s L a m o m K Wu w w M M Z on 3 Wm Q T fiA 93: 523 R 9413C mmawwwwa 5&3 EESQEE .1 4 m W $5.223 H y mi m; $35 5%NEZZNFm wunmmwua d 4 mohfiawwu 539m 95 MNDmmwNE .rzd jwaoun 3 m Na 3 OHw0QOPm yZFr 223a molZuDP/Qm umjoou wNE dwk zu mwusm .runooma LUJQONEUnited States Patent 3,232,324 METHOD AND APPARATUS FOR FILLING AERQSOLDISPENSERS Herbert Z. Soho], West Palm Beach, Fla, assignor, by mesneassignments, to American Lecithin Company, Atlanta, (12., a corporationof Georgia Filed Jan. 18, 1963, Ser. No. 252,420 15 Claims. (Cl. 141-3)The present invention relates to a method and system of apparatus forfilling aerosol dispensers. More specifically, the present inventionrelates to method :and apparatus for the filling of aerosol dispenserswith a liquid product and a normally gaseous propellant which is solublein the product.

In recent years, aerosol dispenser-s have come into widespread use.Among the typical applications of aerosols are the spraying of paints,lacquers and other coatings. Many medicinal, cosmetic and food productsare also now available in the form of aerosol sprays. In view of therapid growth of the market for aerosol products, considerable attentionhas been devoted to the development of techniques and apparatus forfilling aerosols, so that they can be efficiently mass produced at highrates of speed.

According to one conventional method for filling aerosols, the desiredamount of liquid product is metered into the aerosol canister. The opencan-ister is then generally purged of air by the introduction of astream of gas. Usually, the purging gas is the same as the gas which isto be used as the propellant in the final product. The canister is thenfitted with a valved closure which is ordinarily crimped in place overthe open mouth of the canister. Next, the canister is advanced to apropellant filling head where a gaseous propellant, soluble in theliquid product, is forced through the valve into the canister.

Since the propellant gases do not immediately dissolve in the product inthe canister, the dispenser is intermittently shaken during thepropellant introduction until enough propellant is introduced to provideexcess gas in the head space in the canister under a head pressure ofabout 100 p.s.i.g.

By such a process, from about 20 to 40 seconds are required to charge acanister of average size, -i.e., of about 14 oz. capacity to the desiredpressure, usually from about 80 to 110 p.s.i.g.

In addition to being slow, another disadvantage of the filling methodjust described stems from the fact that it is essentially anon-continuous process. Each canister must be partially charged withpropellant, shaken to dissolve the gas in the product and then chargedwith additional increments of the propellant until the necessary amounthas been introduced. The interruption for shaking, therefore, holds upthe entire process and results in considerable inefiiciency, especiallywhere large scale production is involved.

Where flammable hydrocarbon propellant gases are employed, thepreviously described, conventional filling method is very hazardous. Thepresence of free propane, butane, isobutane, dimethyl ether, methylchloride or other flammable propellants for purging or at the fillinghead presents a serious danger of fire or explosion. The use of suchpropellants in common filling methods, therefore, requires specialsafety precautions and equipment to minimize the danger.

Therefore, the known aerosol filling methods, exemplified by the onedescribed above, have been characterized by lack of speed, by beingnon-continuous and by the necessity for intermittent shaking of thecanister to bring about solution of the propellant gas in the product. Adanger of fire or explosion has also been present where the solublepropellant gas is of a flammable nature.

Accordingly, it is an object of the present invention to provide amethod and apparatus for filling aerosol containers in a manner whichmeets the needs of assembly line or mass production operations.

Another object of this invention is to provide a method and apparatusfor filling aerosol dispensers at a much higher speed than is possibleby conventional procedures.

A further object of the present invention is to provide a method andapparatus for continuously filling aerosol containers with a liquidproduct and a propellant gas which is soluble in the product.

Another object of the invention is the provision of a method andapparatus for filling an aerosol container with a liquid product and apropellant gas soluble in the liquid without the need for intermittentshaking of the container to dissolve the gas as it is introduced.

An additional object of this invention is to provide a method andapparaus for filling aerosol containers which substantially lessens thehazard of fire or explosion when a flammable, soluble propellant gas isemployed.

The manner in which the above-noted objects and many other highlydesirable objects and advantages of the invention are achieved will befully apparent in the light of the following detailed description of theinvention and the accompanying drawing which represents, by way ofexample, a preferred embodiment of the present invention.

In the drawing, the single figure is a flow diagram of the process ofthe invention and is a schematic represent-ation of the system ofapparatus employed for carrying out the process.

In general, the present invention comprises precooling the liquidproduct, saturating the product with the desired amount of propellantgas, purging the canister, capping the canister with a conventionalvalved closure and then introducing the saturated product through thevalve into the canister under high pressure.

Referring to the figure of the drawing for a more detailed understandingof the invention, it will be seen that the system comprises a storagetank 10 for the liquid product. The product is continuously withdrawnfrom tank 10 during operation of the system and is preferably passedthrough a filter 11 before being fed through precooler 12. Thepre-cooler 12 has the capacity to cool a sufficient quantity of liquidproduct to the desired temperature so that the filling head will have anuninterrupted and ample supply of product during operation.

The temperature of the product is generally reduced below roomtemperature, the particular temperature depending upon the specificproduct-propellant system being employed. For most common systems ofproduct and propellant, a temperature in the range of from about 0 F. to60 F. is satisfactory.

The pre-cooler 12 may consist of a heat-exchanger and a refrigeratorcompressor or other suitable cooling means.

After the pre-cooler 12, the liquid next passes through a saturator 13.Soluble propellant gas from storage unit 14 is also fed into thesaturator and is intimately mixed with the pro-cooled product to insurerapid solution. The propellant is preferably supplied to the saturatorunder a pressure of from 5 to p.s.i.g. The saturator may be insulated tominimize temperature change during saturation. Carbon dioxide, nitrousoxide, nitrogen and mix tures thereof are among the most commonlyemployed and most satisfactory propellant gases.

When the product is saturated with the desired amount of propellant gas,it is forced by pump 15 under high pressure to filling head 20. A surgetank 16, pressure regulator 17, strainer 18 and sight gauge 19 may beinserted between the pump 15 and the filling head 20. The surge tank 16dampens pressure variations due to the pump cycle. The pressureregulator 17 and gauge 19 enable the line pressure to be controlled andmonitored a. it so that the operator can verify that the proper fillingpressure is obtained. The strainer, of course, eliminates any foreignbodies which might clog the filling equipment or the valves ofindividual canisters.

Pump is operated so as to provide a pressure on the output or fillinghead side of from about 400 to 700 p.s.i.g. This keeps the propellant insolution and enables the canisters to be filled through their valves athigh speed.

Before arriving at the filling head 20, the individual open canistersare preferably advanced to a pre-purger 21 where the air is purged by alow-pressure flow of purging gas, preferably propellant gas. Next, thecanisters are moved to a capper 22 where a valved closure is crimped inplace, thus closing the open mouth of the canister. Then, the canisteris advanced to a pressure-purger 23. In this instance, purging isaccomplished by the introduction of propellant gas through the valveunder a positive pressure of from about 0.1 to 50.0 p.s.i.g.

Finally, the purged canister is moved to the filling head wherepre-cooled product saturated with soluble propellant gas is forcedthrough the valve under high pressure in the range of from about 400 to700 p.s.i.g.

The filling head may comprise an adjustable electronic timer forcontrolling the length of the filling cycle to suit the volume of thecanister and the nature of the product propellant system being charged.The filling head itself is simply a device which is capable of engagingthe valve of the canister and opening it so that the canister may befilled with material pumped through the filling head.

By the present method, only about 2 or 3 seconds are required to fill an14 oz. canister to a pressure of from about 80-ll0 p.s.i.g. as comparedwith from 20 to seconds required for filling aerosol containersaccording to the conventional methods described above.

Where a flammable propellant gas is to be employed, the prepurging maybe eliminated to reduce the fire hazard. The pressure purging may alsobe omitted when such propellants are employed, and the can may simply beevacuated prior to filling. Alternatively, the canister may beevacuated, pressure-purged and then filled. In any event, the danger offire or explosion is substantially reduced by virtue of thepre-saturation of the product with the propellant. Since the propellantis in solution throughout most of this filling process, the likelihoodof fire or explosion is minimized.

The purging of the canister may also be varied as described in thepreceding paragraph, even where non-flammable propellants are utilized.The pie-purging and pressure-purging gases may be the same. as thepropellant gas in which case it may be convenient to use purging gasfrom supply tank 14.

In general, a void or space of from about 20% to 25% of the canistervolume is maintained after filling so that the complete contents can bedischarged under sufiicient pressure to produce a satisfactory spraypattern.

Canisters may be filled by the present method while in either theupright or inverted position. Of course, in the inverted position, moredissolved propellant gas escapes from the saturated product than whenthe canister is filled in the upright position. In the upright position,the newly introduced product arrives below the level of the previouslycharged product so that the gas must bubble up through the first part ofthe product. This tends to hold the gas in solution.

It will be obvious to one skilled in the art that various propellantgases may be employed other than those previously mentioned. Likewise,the invention is useful with products having a wide variety of liquidbases including water, alcohols, saturated hydrocarbons and the like.Liquid dispersion, emulsions and mixtures may also be filled accordingto this method.

In practicising the invention, a number of variables may be controlledto arrive at the proper filling of the canisters. For example, bymanipulating the pre-cooling temperature, the pressure of the propellantgas in the saturator and the amount of gas introduced into the canduring purging, the final pressure in the filled can may be controlled.

While the present invention has been described with reference to certainpreferred embodiments, it will be obvious to those skilled in the artthat various changes and modifications may be made in both the methodand system without departing essentially from the spirit of theinvention or the scope of the following claims.

What is claimed is:

1. A method for filling an aerosol dispenser with a liquid product and apropellant gas which is soluble in said product comprising pre-coolingsaid product,

saturating said pre-cooled product with said propellant purging saiddispenser to remove air, and

pumping said pre-cooled product saturated with said propellant gas intosaid dispenser under high pressure.

2. A method for filling an aerosol dispenser having a valve with aliquid product and a propellant gas which is soluble in said productcomprising pre-cooling said product,

saturating said product with said propellant gas,

purging said dispenser to remove air, and

introducing said pre-cooled product saturated with said propellant gasthrough said valve and into said dispenser under high pressure. 3. Amethod for filling an aerosol dispenser having a valve with a liquidproduct and a propellant gas which is soluble in said product comprisingpre-cooling said product, saturating said pre-cooled product withpropellant gas under a pressure of from about 5 to 150 p.s.i.g.,

pre-purging said dispenser while still open to remove air by displacingsaid air with a low pressure flow of a purging gas other than air,

closing said dispenser,

pressure-purging said dispenser by introducing a purging gas other thanair through said valve under a pressure of from 0.1 to 50 p.s.i.g., and

pumping said pre-cooled product saturated with propellant gas throughsaid valve and into said purged dispenser under a high pressure of from400 to 700 p.s.1.g.

4. The method of claim 3 wherein said propellant gas is one selectedfrom the group consisting of carbon dioxide, nitrous oxide and nitrogen.

5. The method of claim 3 wherein said purging gas is the same as saidpropellant gas.

6. The method of claim 3 wherein said product is pre-cooled to atemperature in the range of from about 0 F. to 60 F.

7. The method of claim 3 further comprising filling said dispenser tofrom to of capacity and to a pressure of from 80 to p.s.i.g.

8. A method for filling an aerosol dispenser having a valve with aliquid product and a propellant gas which is soluble in said productcomprising pre-cooling said product,

saturating said pre-cooled product with a propellant gas which issoluble in said product,

evacuating said dispenser and pumping said pre-cooled product saturatedwith said propellant gas through said valve and into said disenser undera pressure of from about 400 to 700 p.s.1.g.

9. The method of claim 8 wherein said propellant is a flammable gas.

10. A system for rapidly and continuously filling an aerosol dispenserhaving a valve with a liquid product and a propellant gas which issoluble in said product comprising cooling means for receiving andpre-cooling said product,

saturatingimeans for receiving said pre-cooled product from said coolingmeans and saturating said precooled product with said propellant gas andmeans for receiving said pre-cooled product saturated with saidpropellant gas from said saturating means and introducing said saturatedpre-cooled product into said dispenser under high pressure.

11. A system for rapidly and continuously filling an aerosol dispenserhaving a valve with a liquid product and a propellant gas which issoluble in said product comprising a heat exchanger for receiving andpre-cooling said product,

a pressure chamber for receiving said pre-cooled product from said heatexchanger and for dissolving said propellant gas in said pre-cooledproduct under pressure,

means for purging air from said dispenser, and

means for receiving said pre-cooled product saturated with saidpropellant from said pressure chamber and introducing said saturated,pre-cooled product through said valve into said dispenser under highpressure.

12. The system of claim 11 wherein said means for introducing saidsaturated, pre-cooled product into said dispensericomprises a pump and afilling head.

13. A system for rapidly and continuously filling an aerosol dispenserhaving a valve with a liquid product and a propellant gas which issoluble in said product comprising a heat exchanger for receiving andpro-cooling said product,

a pressure chamber for receiving said pre-cooled product from said heatexchanger and dissolving said propellant gas in said pre-cooled productunder pressure,

means for purging air from said dispenser while said canister is stillopen,

means for capping said dispenser with a cap having a valve therein,

means for further purging said dispenser by introducing purging gasthrough said valve, and

5 means for receiving said pre-cooled product saturated with saidpropellant gas from said pressure chamber and introducing saidsaturated, pre-cooled product through said valve and into said dispenserunder high pressure.

14. A method for filling an aerosol canister having a valve with aliquid product and a propellant gas which is soluble in said productcomprising pre-cooli-ng said product,

saturating said pre-cooled product with a propellant gas which issoluble in said product,

evacuating said canister, and

pumping said pre-cooled product saturated with said propellant gas intosaid canister under high pressure.

15. A system for filling an aerosol container having a valve with aliquid product and a propellant gas which is soluble in said productcomprising cooling means to lower the temperature of said product,

means saturating said pre-cooled product with a propellant gas,

means to evacuate said container, and pump means for forcing saidpre-cooled product saturated with said propellant gas into saidcontainer under high pressure.

References Cited by the Examiner UNITED STATES PATENTS LAVERNE D.GEIGER, Primary Examiner.

1. A METHOD FOR FILLING AN AEROSOL DISPENSER WITH A LIQUID PRODUCT AND APROPELLANT GAS WHICH IS SOLUBLE IN SAID PRODUCT COMPRISING PRE-COOLINGSAID PRODUCT. SATURATING SAID PRE-COOLED PRODUCT WITH SAID PROPELLANTGAS, PURGING SAID DISPENSER TO MOVE AIR, AND PUMPING SAID PRE-COOLEDPRODUCT SATURATED WITH SAID PROPELLANT GAS INTO SAID DISPENSER UNDERHIGH PRESSURE.